Some luminous cups have heretofore been known. For instance, one conventional luminous cup comprises a housing, a capsule placed in a space between the inner and outer bottom walls of the housing, and two different liquid agents filled, respectively, in the space and in the capsule. The liquid agents are capable of chemiluminescence upon reaction with one another. When the capsule is broken by a user, the liquid agents are mixed together to cause chemiluminescence, and the generated light projects out through the outer wall. By virtue of the light, the user can easily handle the cup, even at night, and enjoy the illumination and other effects. In another conventional luminous cup, a plurality of the capsules is arranged vertically in a space between the inner and outer sidewalls of the housing. However, the capsules of the conventional cups have been formed in straight shapes. This causes the following disadvantages in addition to the restriction on the location of the capsule chamber for receiving the capsules therein.
Firstly, in the cup having the capsules placed in the bottom portion of the housing, the small space of the bottom portion sets a limit on the number of the capsules, and thereby the capsules cannot have a large diameter. As a result, the limited volume of the liquid agent in the capsules makes it difficult to achieve an optimum ratio of the two liquid agents for chemiluminescence. Further, since the capsules are housed in the bottom portions, it is more difficult to break the capsules by external force or manual operation. If the capsules are successfully broken, the agents in the capsules are not adequately mixed with the other agents because the other agents are in the side portions of the housings.
Secondly, in a cup having the capsules vertically in the side portion of the housing, the capsule chamber creates a protrusion extending outward or inward in the side portion. This deteriorates the aesthetic configuration of the cup. The increased thickness of the side portion makes it difficult to stack the plurality of cups by fitting one within another, resulting in increased storage space requirements and degraded portability. Further, in order to obtain the chemiluminescence, it is necessary to bend the side portion of the housing repeatedly due to the number of the capsules. The liquid agents in the capsules are distributed unevenly around the capsule chambers arranged vertically. This provides strong lights only in certain portions and the entire cup cannot give off light evenly.